This invention relates to a remote shifting system for a marine propulsion unit and more particularly to an improved and simplified electronically controlled remote shift mechanism for a marine outboard drive.
As is well known, most marine propulsion units include a forward neutral reverse transmission which permits the watercraft to be operated in either forward or reverse drive mode or in a neutral condition. Frequently, it is desirable to provide a remote actuator for actuating the transmission, which is generally positioned with the outboard drive portion of the propulsion unit and frequently in its lower unit. One type of remote control mechanism which has been employed incorporates an electric follow-up system wherein the operator controls a remote shift lever which, in turn, transmits a position signal to a remote servo motor for actuating the transmission control to the selected position. Such systems normally employ a potentiometer on the transmission shift lever and on the shift control with a comparator circuit to determine discrepancies in the two positions so as to operate a motor to bring coincidence into the two positions. Although such arrangements are satisfactory, the use of two potentiometers can give rise to expense in the control mechanism.
In order to reduce the cost of the system, it would be desirable to employ only position responsive switches at the transmission control end. However, when only position responsive switches are employed it is impossible for the system to determine when the transmission control is in an intermediate position between its forward, neutral and reverse positions.
It is, therefore, a principal object of this invention to provide an improved remote shifting system for a marine propulsion unit which permits the use of position responsive switches in the control mechanism.
It is a further object of this invention to provide a control routine for a remote shifting system for a marine propulsion unit that permits the use of only position responsive switches in the transmission control.